In the light of low angle target direction of arrival (DOA) estimation problem of MIMO radar under condition of multipath, a DOA estimation algorithm with sample multiplexing at low angle multi-path target of MIMO radar based on FBSS (Forward-Backward with spatial smoothing) is proposed. In consideration of the difference between the coherent signal and multi-path signal DOA estimation of MIMO radar, four path model of MIMO radar echo signal is adopted by algorithm to obtain the virtual array by the matched filter according to the Waveform diversity of MIMO radar, and to reuse the virtual array by rows and columns for FBSS, thus effectively improving the low angle target DOA estimation accuracy on the condition of low signal-to-noise ratio. The simulation results show that the RMSE of the proposed algorithm is reduced by an average of 1 degree compared with the M-SSMUSIC when the SNR less than -12dB.